Muscles of the Eye Flashcards
What are the different categories of the occular muscles?
Intrinsic muscles
Extrinsic muscles
What do the intrinsic muscles do?
Controls the pupil diameter and helps lens curvature to enable us to see near objects
What do the extrinsic muscles do?
Move the eye
What are the 6 extrinsic muscles?
4 straight muscles called recti:
medial rectus
lateral rectus
inferior rectus
superior rectus
2 oblique msucles:
superior oblique
inferior oblique
Where do the recti extrinsic muscles arise from?
Apex of the orbit from an annular fibrous ring
Where does the superior oblique muscle arise from?
Roof of the orbit posteriorly
Where does the inferior oblique muscle arise from?
Floor of orbit anteriorly
What muscle runs to the upper eyelid and elevates it?
Levator palpebrae superioris
Where does the levator palpebrae superioris lie?
Above the superior rectus muscle
What is the origin of the levator palpebrae superioris?
Roof of orbit
What is the insertion of the levator palpebrae superioris?
Upper eyelid
What is the origin of all recti muscles?
Tendinous ring
What is the insertion of all recti muscles?
Sclera anteriorly
What is the origin of the superior oblique muscle?
Lesser wing of sphenoid
What is the insertion of the superior oblique muscle?
Sclera posteriorly
What is the origin of the inferior oblique muscle?
Medial part of orbit floor
What is the insertion of the inferior oblique muscle?
Sclera posteriorly
What are factors that affect the way muscles pull the eye?
Axis of orbit vs eyeball (muscles are attached along orbital axis not optical axis, so they pull at an angle and each muscle has more than one action)
Where the muscles attaches to sclera in relation to the equator of the eye (oblique muscles are attached to posterior part fo they pull posterior part up/down and anterior part moves in the opposite direction)
What are uniocular eye movements?
What are binocular eye movements?
What is intorsion?
When the top of the eyeball rotates towards the nose
What is extorsion?
When the top of the eyeball rotates away from the nose
Each muscle has a primary, maybe secondary, and maybe tertiary action. What are the action(s) of the medial rectus?
Primary - adduction
Secondary - none
Tertiary - none
Each muscle has a primary, maybe secondary, and maybe tertiary action. What are the action(s) of the lateral rectus?
Primary - abduction
Secondary - none
Tertiary - none
Each muscle has a primary, maybe secondary, and maybe tertiary action. What are the action(s) of the superior rectus?
Primary - elevation
Secondary - adduction
Tertiary - intorsion
Each muscle has a primary, maybe secondary, and maybe tertiary action. What are the action(s) of the inferior rectus?
Primary - depressoin
Secondary - adduction
Tertiary - extorsion